Greetings
I've been lurking around this board a while. (I'm a fan, not an umpire, and its nice to be able to know the rules and the myths.)
If you go to the IOC website, you can find their meeting/parliamentary rules in their charter. I copied the links below.
The parliamentary rules look basic, unless they have more un-posted. (But they don't mention any other rules of order authority.)
You cannot proxy.
Not voting (for what ever reason) is abstaining. Only the votes cast are counted in calculating the majority.
Looking at the reasons to refrain from voting, business interests (at least sporting good sales) do not appear to be one of them. And the Chairman can make the call. (An interesting rule in and of itself.)
http://multimedia.olympic.org/pdf/en_report_122.pdf
Charter (see page 41 for proxy and situations when not to vote.)
http://multimedia.olympic.org/pdf/en_report_942.pdf
Summary of meeting rules
Joe